Impeller apparatus for water pump and water pump

ABSTRACT

An impeller apparatus for a water pump includes a driven side rotation body having a shaft portion and a plane portion positioned outside of the shaft portion in a radial direction, the driven side rotation body being arranged coaxially to a drive side rotation body which operates an auxiliary and being connected to the drive side rotation body through the plane portion and an intermediate member provided on an internal periphery of the drive side rotation body to project inwardly in a radial direction to integrally rotate with the drive side rotation body, and an impeller attached on the shaft portion to integrally rotate with the driven side rotation body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119with respect to Japanese Patent Application No. 2005-086906 filed onMar. 24, 2005, the entire content of which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to an impeller apparatus for a water pumpand a water pump.

BACKGROUND

There are various known water pumps. For example, JPH08-100652A (FIG. 3)describes a water pump which includes a drive shaft (38) serving as adrive side rotation body for operating an auxiliary, a driven siderotation body (36) arranged coaxially with and connected to the driveshaft for integrally rotating, and a pump impeller (37) which integrallyrotates with the driven side rotation body. According to theconstruction of the foregoing water pump, the drive shaft and the drivenside rotation body are coaxially connected at the shaft center by meansof a dog and cam joint or bolt-nut fastening, and the power from thedrive shaft is transmitted to the impeller.

A water pump described in JP2004-52723A (FIG. 1) includes driven siderotation bodies (18, 25) which are arranged in parallel with an outputshaft of an engine serving as a drive side rotation body, and a pumpimpeller 30 which integrally rotates with the driven side rotation body.With the construction of the foregoing water pump, the output shaft ofthe engine and the driven side rotation body are connected by means of abelt to transmit the power from the output shaft.

Because the water pump described in JPH08-100652A is positioned inside acrankcase, the water pump cannot have a visual check. Further, becausethe driven side rotation body is coaxially and directly connected to thedrive shaft at the center of the shaft, high accuracy is required for analignment of the drive shaft and the driven side rotation body, whichincreases manufacturing cost in order to maintain the precision. Stillfurther, because the auxiliary, a connecting portion (e.g., a joint),and the water pump are aligned along an axial direction, the spacenecessary to be ensured for positioning the auxiliary the connectingportion and the water pump in the axial direction is increased.

Particularly, when the drive side rotation body and the driven siderotation body are connected by means of a dog and cam joint and when thejoint is made of rigid material (e.g., metal), noise may be generated bymetal-to metal contact of the joint.

On the other hand, the water pump described in JP2004-52723 requiresensuring the space for manageability of the belt exclusive foractivating the water pump. Further, an outer shape of a pulley servingas the driven side rotation body is required to have highly preciseroundness in order to smoothly transmit the rotation, and themanufacturing cost is increased in order to ensure the accuracy.Further, because load from the belt is directly applied to the waterpump, parts (e.g., a pulley, a body, and a bearing) are required to haveadequate strength and durability.

A need thus exists for an impeller apparatus for a water pump and awater pump, which rotates an impeller by transmitting rotation of thedrive side rotation body which operates an auxiliary to the driven siderotation body.

SUMMARY OF THE INVENTION

In light of the foregoing, the present invention provides an impellerapparatus for a water pump, which includes a driven side rotation bodyhaving a shaft portion and a plane portion positioned outside of theshaft portion in a radial direction, the driven side rotation body beingarranged coaxially to a drive side rotation body which operates anauxiliary and being connected to the drive side rotation body throughthe plane portion and an intermediate member provided on an internalperiphery of the drive side rotation body to project inwardly in aradial direction to integrally rotate with the drive side rotation body,and an impeller attached on the shaft portion to integrally rotate withthe driven side rotation body.

According to another aspect of the present invention, a water pumpincludes a body, a housing fixed to the body, a driven side rotationbody having a shaft portion extended to the housing at a first side anda plane portion arranged at outside in a radial direction of the shaftportion, the driven side rotation body being rotatable with the body, animpeller attached at the first side of the shaft portion to integrallyrotate with the driven side rotation body, and a drive side rotationbody arranged coaxially to the driven side rotation body and having anintermediate member provided projecting from the outside in the radialdirection of the plane portion to the plane portion to engage with theplane portion, the drive side rotation body for transmitting rotationalforce to the driven side rotation body through the intermediate member.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of the presentinvention will become more apparent from the following detaileddescription considered with reference to the accompanying drawings,wherein:

FIG. 1 is a plan view showing a water pump according to an embodiment ofthe present invention.

FIG. 2 is a cross-sectional view of the water pump according to theembodiment of the present invention.

FIG. 3 is a plan view showing a first modified example according to thepresent invention.

FIG. 4 is a plan view showing a second modified example according to thepresent invention.

FIG. 5 is a plan view showing a third modified example according to thepresent invention.

FIG. 6A is a lateral view showing a shaft according to the thirdmodified example of the present invention.

FIG. 6B is a cross-sectional view showing the shaft according to thethird modified example of the present invention.

DETAILED DESCRIPTION

An embodiment of the present invention will be explained with referenceto illustrations of drawing figures as follows. As shown in FIGS. 1-2, awater pump 10 includes a body 11 which is connected to a housing 90through a gasket 80, or the like, by means of a fastening means 12. Thebody 11 includes a stepwise cylindrical portion having a large diameterportion 11 a and a small diameter portion 11 b. An inner race of abearing 13 is press-fitted onto an external periphery of the smalldiameter portion 11 b.

A shaft 21 serving as a drive side rotation body is fixed on an outerrace of the bearing 13. That is, the shaft 21 is formed by stamping, forexample, a steel plate, and integrally includes a shaft portion 22, anarm portion 23, and plural (e.g., four) extended portions 24. The armportion 23 is formed continuously from a base portion (i.e., an openingbase portion) in an axial direction of the shaft portion 22, and in acylindrical configuration having a bottom outwardly in a radialdirection, and opens in an opposite direction of the shaft portion 22.As shown in FIG. 2, the shaft 21 is supported by press-fitting anexternal peripheral portion 23 a of the arm portion 23 onto an externalperiphery of the outer race of the bearing 13. Thus, the shaft 21 isrotatably supported by the bearing 13, or the like.

Each of the extended portions 24 extends by a predetermined angle (e.g.,90 degrees) outwardly in a radial direction continuously from an openingbase portion of the arm portion 23, and includes a plane portion 24 aformed by bending a tip side of the extended portion 24 in an oppositedirection of the shaft portion 22 to be in parallel to an axialdirection of the shaft. As shown in FIG. 2, more particularly, the planeportions 24 a are formed by bending plural (e.g., four) plate portionsP1 which extends outwardly in a radial direction continuously from anopening base portion of the arm portion 23 by a predetermined angle(e.g., 90 degrees) to be in parallel to the axial direction of theshaft. As shown in FIG. 1, each of the plane portions 24 a is evenlyarranged in a peripheral direction (i.e., a tangential direction aroundshaft center O at the center of the plane portion 24 a in a peripheraldirection), and the plane portions 24 a are formed to be line symmetryrelative to each corresponding meridian section L1, L2. The extendedportion 24 is connected to an auxiliary (i.e., an auxiliary other thanthe water pump 10).

As shown in FIG. 2, an impeller 25 is fitted onto a tip portion of theshaft portion 22 in an axial direction to be integrally rotatable. Theimpeller 25 is positioned in a water chamber 91 formed by closing anopening of a concave portion of the housing 90 by the body 11. The waterchamber 91 is an element of an engine cooling water channel.

A mechanical seal 26 is provided between an external periphery of theshaft portion 22 and an internal periphery of the large diameter portion11 a of the body 11 to seal between the water chamber 91 and the bearing13. The mechanical seal 26 separates the water chamber 91 hermeticallyfrom the outside so that the cooling water does not leak to the outside(i.e., bearing 13 side).

The shaft 21 is connected to a pulley 31 serving as a drive siderotation body which operates the auxiliary through plural (e.g., four)intermediate members 41 to integrally rotate with the pulley 31. Moreparticularly, the pulley 31 is formed cylindrically having a bottom andopens towards the shaft 21 side, and rotates integrally with a driveshaft which is secured to an attaching hole 31 b provided in the centerthereof by transmitting the power from the output shaft of the engine bymeans of a belt applied to an external periphery portion 31 a of thepulley 31. The pulley 31 activates the auxiliary through the drive shaftwhich is secured to the attaching hole 31 b.

The pulley 31 is arranged coaxially to the shaft 21 (i.e. shaft portion22) on the shaft center O. The plural intermediate members 41 areconnected to the pulley 31 to integrally rotate each other. Each of theintermediate members 41 is made of flexible material such as rubber orresin. Length of the intermediate member 41 in the axial direction isshorter than the length of an internal periphery of the pulley 31. Theintermediate members 41 are provided projecting from an internalperiphery of the pulley 31 inwardly in a radial direction, and arefastened to the pulley 31 by means of a fastening bolt 42. In thiscircumstance, all of the intermediate members 41 are accommodated insidethe pulley 31.

A face of the intermediate member 41 at internal peripheral sideincludes an engaging surface 41 a which faces the plane portion 24 a ina radial direction and is engaged with the plane portion 24 a.Accordingly, a part of the shaft 21 (i.e., arm portion 23, and extendedportion 24) is housed inside of the intermediate member 41 along withother parts such as the bearing 13. As shown in FIG. 1, each of theengaging surfaces 41 a is evenly extended in a peripheral directionwhich is perpendicular to the meridian section L1, L2 which runs throughon the center of the engaging surface 41 a in the peripheral direction(i.e., a tangential direction around the shaft center O at the center ofthe engaging surface 41 a in the peripheral direction) (i.e., each ofthe engaging surfaces 41 a is arranged to be either perpendicular to orin parallel to the meridian section L1, L2). And each of the engagingsurfaces 41 a is formed to be line symmetry relative to the meridiansection L1, L2. A width of the engaging surfaces 41 a in the peripheraldirection is shorter than a width of the plane portion 24 a. Further,when the meridian section L1, L2 which is drawn though the center of theengaging surface crosses the center of the plane portion 24 a in theperipheral direction, each of the engaging surfaces 41 a is set at aposition where the length from the shaft center O to the plane portion42 a in the radial direction is slightely longer than the length fromthe shaft center O to the engaging surface 41 a.

Accordingly, a clearance C is formed between the engaging surface 41 aand the plane portion 24 a when the meridian section L1, L2 which runsthrough the center of the engaging surface 41 a crosses the center ofthe plane portion 24 a in the peripheral direction. The clearance Cabsorbs deviation of the shaft center when assembling the pulley 31which is provided with the intermediate member 41 to the shaft 21.

Thus, the shaft 21 which engages with the engaging surface 41 a at theplane portion 24 a integrally rotates with the pulley 31 by pushing theplane portion 24 a onto the engaging surface 41 a in accordance with therotation of the pulley 31.

When the power from the output shaft of the engine is transmitted to thepulley 31 through the belt applied on the external peripheral portion 31a of the pulley 31 with the foregoing construction, the pulley 31activates the auxiliary in accordance with the rotation thereof throughthe drive shaft secured to the attaching hole 31 b. In thiscircumstance, the rotation of the pulley 31 is transmitted to the shaft21 through the intermediate member 41, and the pulley 31 and the shaft21 integrally rotate. Then, the impeller 25 which is unitarily providedon the shaft 21 rotates in the water chamber 91. Accordingly, thecooling water filled in the water chamber 91 is pushed out to be acurrent of the cooling water which circulates in the cooling waterchannel.

According to the embodiment of the present invention, the followingeffects can be obtained.

According to the embodiment of the present invention, the rotation ofthe pulley 31 which activates the auxiliary is transmitted to the shaft21 through the plane portion 24 a engaged with the intermediate member41 to rotate the impeller 25. Although the pulley 31 and the shaft 21for the transmission of the rotation are coaxially arranged, precisionrequired for aligning the pulley 31 and the shaft 21 can be reducedbecause a deviation of the shaft center of the pulley 31 and the shaft21 can be absorbed by slides between the plane surface 24 a of theextended portion 24 and intermediate member 41 along the plane portion24 a. For example, the precision for assembling the shaft 21 to thepulley 31 can be reduced through the plane portion 24 a which is engagedwith the intermediate member 41.

Further, because highly precise roundness is not required for the drivenside rotation body compared to the case for transmitting the rotation ofthe drive side rotation body (i.e., pulley) to the driven side rotationbody (i.e., shaft) through the belt, it is allowed to reduce themanufacturing quality (i.e., machining accuracy). Because it is notnecessary to have manageability of the belt exclusively for the waterpump, the space can be effectively used.

According to the embodiment of the present invention, because the planeportion 24 a is formed by bending the plate portion P1 extendedoutwardly in the radial direction to be in parallel to the axialdirection, the plane portion 42 a can be formed easily by bending, andthus the manufacturing cost of the shaft 21 is reduced.

According to the embodiment of the present invention, by housing theplane portion 24 a inside the pulley 31 having a cylindrical shape witha bottom along with a part of the shaft 21 (e.g., arm portion 23), thepulley 31, the intermediate member 41, and the shaft 21 are connected ata position in an axial direction which overlaps with the pulley 31 inthe radial direction. Because the pulley 31, the intermediate member 41,and the shaft 21 are connected overlapped one another in the radialdirection, space necessary to be ensured in the axial direction as awhole can be reduced.

According to the embodiment of the present invention, the water pump 10which can rotate the impeller 25 by transmitting the rotation of thepulley 31 which activates the auxiliary to the shaft 21 withoutrequiring high precision for the assembling and machining, is provided.

According to the embodiment of the present invention, the intermediatemember 41 is made of flexible material. With this construction, becausethe rotation between the pulley 31 and the shaft 21 is buffered by theintermediate member 41 to be transmitted, generation of a noise can berestrained.

According to the embodiment of the present invention, because the loadapplied to the belt is not directly applied to the water pump 10, thestrength and the durability required for the parts (e.g., body 11,bearing 13) can be moderated. Thus, longevity of the parts of the waterpump 10 can be increased, and providing the capability of the excessiveperformance to the water pump is avoided to reduce the manufacturingcost. Particularly, because the strength required for the bearing 13 ismoderated, and the bearing 13 can be reduced in size.

According to the embodiment of the present invention, because the waterpump 10 and the auxiliary other than the water pump 10 can be arrangedto activate coaxially, the loading capacity of the water pump 10 in theengine can be improved.

According to the embodiment of the present invention, because a part ofthe water pump 10 is enclosed by the pulley 31, infiltration of externalobjects into the inside of the bearing 13 can be restrained.

According to the embodiment of the present invention, because the waterpump 10 is fixed on the housing 90 as an outside attachment, a visualcheck can be conducted easily.

The foregoing embodiment can be varied and modified, for example, asfollows.

The number of the plane portion 24 a and the intermediate member 41 canbe varied from one to any plural numbers. In case the plural planeportions 24 a and the intermediate members 41 are provided, it ispreferable to arrange plane portion and the intermediate member whichmake a pair evenly by a predetermined angle considering balancing fortransmitting the rotation.

For example, the water pump 10 includes a shaft 46, shown in FIG. 3,including plane portions 46 a unevenly provided in a rotationaldirection, and intermediate members 47 corresponding to the planeportion 46 a are provided on the pulley 31. That is, at the planeportion 46 a, length D1 from an intersection I between the plane portion46 a and meridian section L3 which crosses vertical to the plane portion46 a to working point W1 of the intermediate member 47 at a mostadvancing side in a rotational direction is set to be longer than lengthD2 from the intersection I to working point W2 of the intermediatemember 47 at a most reverse side in a rotational direction. In thosecircumstances, length R1 from the shaft center O to the working point WIof the intermediate member 47 at the most advancing side in therotational direction is set to be longer than length R2 from the shaftcenter O to the working point W2 of the intermediate member 47 at themost reverse side in the rotational direction, and thus a drive torqueto be transmitted to the shaft 46 (i.e., plane portion 46 a) isincreased compared to the case where the length R1 and the length R2 areset to be equal.

With the shaft 46 shown in FIG. 3, it is set that line L5 in aperipheral direction (i.e., a tangential direction around the shaftcenter O at the center of the intermediate member 47 in a peripheraldirection) which is vertical to meridian section L4 which runs throughthe center of the intermediate member 47 in a peripheral direction andan extended line L6 of the plane portion 46 a crosses. Accordingly, theplane portion 46 a increases an element of rotational force receivedfrom the intermediate member 47, and thus increases the efficiency inrotation.

A second modified example will be explained as follows. As shown in FIG.4, the water pump 10 includes a shaft 48 including further unevenlyarranged plane portions 48a in a rotational direction. An intermediatemember 49 corresponding to each of the plane portion 48a is arrangedunevenly from a fixing portion (i.e., fastening bolt 42) in a rotationaldirection.

A third modified example will be explained as follows. As shown in FIGS.5 and 6A, 6B, the water pump 10 includes a shaft 51 which includesplural (e.g., six) plane portions 51 a continuously provided each otherfor forming a polygonal cylinder (e.g., hexagon). As shown in FIG. 6B,the plane portion 51 a is formed by bending an annular plate portion P2formed continuously from an opening end portion of the arm portion 23and extended outwardly in a radial direction in an opposite direction ofthe shaft portion 22 in an axial direction. The plane portions 51 a areformed by stamping (drawing), and a recess 51 b is formed betweenadjacent plane portions 51 a for facilitate the processing. Theintermediate member 41 is provided on the pulley 31 and projects fromthe internal periphery of the pulley inwardly in a radial direction. Theintermediate members 41 are provided on one of a pair of plane portions(i.e., two plane portions) which faces each other in a radial direction.The number of the intermediate member 41 may be equal to or more thanone (i.e., up to six for a hexagonal cylinder), and it is preferablethat the number of the intermediate member 41 is to be even number(e.g., two, four, or six) considering the balancing for transmitting therotation. With the construction of the third modified example, becausethe plural plane portions 51 a are formed continuously to form thepolygonal cylinder, the strength of the plural plane portions 51 a canbe ensured.

The intermediate members 41, 47, 49 may be made of rigid material suchas metal.

In this case, the strength of the intermediate members 41, 47, 49 can beensured with a simple manufacturing method.

According to the embodiment of the present invention, the pulley 31 andthe shaft 21, or the like, may be arranged separately in an axialdirection. For example, the drive shaft secured to the pulley 31 (i.e.,attaching hole 31 b) is extended to the intermediate member 41 side, anda fixing portion serving as the drive side rotation body which isconnectable to the intermediate member 41 is secured to the drive shaft.At the fixing portion, the shaft 21 is coaxially connected to the pulley31 through the intermediate member 41. In this case, as freedom ofplacement of the pulley 31 in the axial direction increased, and thedesign freedom can be increased.

According to the embodiment of the present invention, although the shaft21 which integrally includes the shaft portion 22, the arm portion 23,and the extended portion 24 is adopted, the shaft 21 may be constructedwith plural parts as long as the shaft 21 is connected to the impeller25 to integrally rotate.

According to the embodiment of the present invention, the shaft 21 maybe manufactured by resin molding or other methods.

Although the drive side rotation body (i.e., pulley 31) which is rotatedby the output shaft of the engine is adopted according to the embodimentof the present invention, other drive side rotation body which isrotated by another drive shaft or by an electric motor. The powertransmission to the drive side rotation body is not limited to thetransmission by means of the belt, and may be transmitted by means of agear engagement, or the like.

According to the embodiment of the present invention, the auxiliarywhich the drive side rotation body (i.e., pulley 31) rotates includes anair conditioner, an alternator, a pump for a power steering, a vacuumpump, or the like.

According to the present invention, a water pump includes a driven siderotation body having a plane portion arranged outside in a radialdirection, the driven side rotation body being arranged coaxially to adrive side rotation body which operates an auxiliary and being connectedto the drive side rotation body through the plane portion and anintermediate member provided on an internal periphery of the drive siderotation body to project inwardly in a radial direction to integrallyrotate with the drive side rotation body, an impeller which integrallyrotates with the driven side rotation body, a body which forms a waterchamber where the impeller is positioned, a bearing provided between thebody and the driven side rotation body to rotatably support the drivenside rotation body, and a mechanical seal which seals between the waterchamber and the bearing.

According to the embodiment of the present invention, the rotation ofthe drive side rotation body which operates the auxiliary is transmittedto the drive side rotation body through the plane portion which isengaged with the intermediate member to rotate the impeller. Althoughthe drive side rotation body and the driven side rotation body fortransmitting the rotation are arranged coaxially, because a deviation ofthe shaft center between the drive side rotation body and the drivenside rotation body can be absorbed by a slide between the plane portionand the intermediate member along the plane portion, the accuracyrequired for alignment can be reduced. For example, the assemblingprecision of the driven side rotation body relative to the drive siderotation body are reduced through the plane portion which engages withthe intermediate member.

According to the embodiment of the present invention, high precision ofthe roundness is not required, and the processing precision can bereduced. Further, because manageability for the belt exclusively for thewater pump is not necessary, space can be used effectively.

According to the embodiment of the present invention, because the planeportion is formed by bending the plate portion extended outwardly in aradial direction to be in parallel to the axial direction, the planeportion can be formed easily by bending.

According to the embodiment of the present invention, the plural planeportions formed by bending the annular plate portion extended outward ina radial direction to be in parallel to the axial direction are arrangedcontinuously to have a polygonal cylindrical configuration, the strengththereof can be ensured.

According to the embodiment of the present invention, the length fromthe intersection of the plane portion and the meridian section whichcrosses vertical to the plane portion to the working point of theintermediate member at the most advancing side in the rotationaldirection is set to be longer than the length from the intersection tothe working point of the intermediate member at the most reversing sidein the rotational direction. Accordingly, at the plane portion, thelength from the shaft center to the working point of the intermediatemember at the most advancing side in the rotational direction is set tobe longer than the length from the shaft center to the working point ofthe intermediate member at the most reversing side in the rotationaldirection, and thus the drive torque which is transmitted to the driveside rotation body is increased compared to the case where the bothlengths are set at the same length.

According to the embodiment of the present invention, the line in theperipheral direction which crosses vertically to the meridian sectionwhich runs through the center of the intermediate member in a peripheraldirection and the extended line of the plane portion cross each other,and elements of the rotational force that the plane portion receivesfrom the intermediate member is increased, and the efficiency of therotation is improved.

According to the embodiment of the present invention, because the planeportion is housed inside of the cylindrical pulley having the bottomalong with the intermediate member, the pulley, the intermediate member,and the driven side rotation body are connected at an axial positionwhich overlaps with the pulley (i.e., drive side rotation body) in aradial direction. Accordingly, the space to ensure in the axialdirection as a whole can be reduced by connecting the pulley, theintermediate member, and the drive side rotation body overlapping in aradial direction.

According to the embodiment of the present invention, the water pumpwhich rotates the pump impeller by transmitting the rotation of thedrive side rotation body which operates the auxiliary without the highassembling precision and processing precision can be provided.

The principles, preferred embodiment and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiment disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

1. An impeller apparatus for a water pump comprising: a driven siderotation body having a shaft portion and a plane portion positionedoutside of the shaft portion in a radial direction, the driven siderotation body being arranged coaxially to a drive side rotation bodywhich operates an auxiliary and being connected to the drive siderotation body through the plane portion and an intermediate memberprovided on an internal periphery of the drive side rotation body toproject inwardly in a radial direction to integrally rotate with thedrive side rotation body; and an impeller attached on the shaft portionto integrally rotate with the driven side rotation body.
 2. The impellerapparatus for the water pump according to claim 1, wherein the planeportion is formed by bending a plate portion extended outwardly in aradial direction from the shaft portion to be in parallel to an axialdirection.
 3. The impeller apparatus for the water pump according toclaim 1, wherein the plane portion includes a plurality of planeportions, and the plurality of plane portions are formed by bending anannular plate portion extended outwardly from the shaft portion in aradial direction to form a polygonal cylindrical configuration being inparallel to an axial direction.
 4. The impeller apparatus for the waterpump according to claim 1, wherein length from an intersection of theplane portion and a meridian section, which is vertical to the planeportion and runs through a shaft center, to a working point of the planeportion with the intermediate member at an advancing side in arotational direction is set to be longer than length from theintersection to a working point of the plane portion at a reversing sidein the rotational direction.
 5. The impeller apparatus for the waterpump according to claim 2, wherein length from an intersection of theplane portion and a meridian section, which is vertical to the planeportion and runs through a shaft center, to a working point of the planeportion with the intermediate member at an advancing side in arotational direction is set to be longer than length from theintersection to a working point of the plane portion at a reversing sidein the rotational direction.
 6. The impeller apparatus for the waterpump according to claim 3, wherein length from an intersection of theplane portion and a meridian section, which is vertical to the planeportion and runs through a shaft center, to a working point of the planeportion with the intermediate member at an advancing side in arotational direction is set to be longer than length from theintersection to a working point of the plane portion at a reversing sidein the rotational direction.
 7. The impeller apparatus for the waterpump according to claim 1, wherein the intermediate member and the planeportion are arranged so that a line which vertically crosses a meridiansection running through a shaft center and the center of theintermediate member in a peripheral direction, and an extended line ofthe plane portion cross each other.
 8. The impeller apparatus for thewater pump according to claim 2, wherein the intermediate member and theplane portion are arranged so that a line which vertically crosses ameridian section running through a shaft center and the center of theintermediate member in a peripheral direction, and an extended line ofthe plane portion cross each other.
 9. The impeller apparatus for thewater pump according to claim 3, wherein the intermediate member and theplane portion are arranged so that a line which vertically crosses ameridian section running through a shaft center and the center of theintermediate member in a peripheral direction, and an extended line ofthe plane portion cross each other.
 10. The impeller apparatus for thewater pump according to claim 1, wherein the drive side rotation body isa cylindrical pulley having a bottom, and the plane portion is housedinside of the pulley along with the intermediate member.
 11. Theimpeller apparatus for the water pump according to claim 1, furthercomprising: the drive side rotation body.
 12. A water pump comprising: abody; a housing fixed to the body; a driven side rotation body having ashaft portion extended to the housing at a first side and a planeportion arranged at outside in a radial direction of the shaft portion,the driven side rotation body being rotatable with the body; an impellerattached at the first side of the shaft portion to integrally rotatewith the driven side rotation body; and a drive side rotation bodyarranged coaxially to the driven side rotation body and having anintermediate member provided projecting from the outside in the radialdirection of the plane portion to the plane portion to engage with theplane portion, the drive side rotation body for transmitting rotationalforce to the driven side rotation body through the intermediate member.13. The water pump according to claim 12, wherein the drive siderotation body is a cylindrical pulley having a bottom which includes anattaching portion to which a drive shaft for operating an auxiliary at abottom portion thereof is attached.
 14. The water pump according toclaim 12, wherein the plane portion is formed by bending a plate portionextended outwardly in a radial direction from the shaft portion.
 15. Thewater pump according to claim 12, wherein the plane portion include aplurality of plane portions, and the plurality of plane portions areformed by bending an annular plate portion which extends outwardly in aradial direction from the shaft portion in a polygonal cylindricalconfiguration to be in parallel to an axial direction.
 16. The waterpump according to claim 12, wherein length from an intersection of theplane portion and a meridian section, which is vertical to the planeportion and runs through a shaft center, to a working point of the planeportion with the intermediate member at an advancing side in arotational direction is set to be longer than length from theintersection to a working point of the plane portion at a reversing sidein the rotational direction.
 17. The water pump according to claim 12,wherein the intermediate member and the plane portion are arranged sothat a line which vertically crosses a meridian section running througha shaft center and the center of the intermediate member in a peripheraldirection, and an extended line of the plane portion cross each other.18. The water pump according to claim 12, wherein the drive siderotation body is a cylindrical pulley having a bottom, and the planeportion is housed inside of the pulley along with the intermediatemember.
 19. The water pump according to claim 12, wherein theintermediate member includes an end face at an internal peripheral sideincluding an engaging surface which is positioned facing the planeportion in a radial direction of the shaft portion.
 20. The water pumpaccording to claim 19, wherein the engaging surface and the planeportion form a clearance therebetween in a radial direction of the shaftportion when a meridian section which runs through a shaft center of theshaft portion and the center of the engaging surface in a peripheraldirection crosses the center of the plane portion in a radial direction.